Non-enzymatic electrochemical malathion sensor based on bimetallic Cu-Co metal-organic gels modified glassy carbon electrode

A non-enzymatic electrochemical sensor based on bimetallic Cu-Co metal-organic gel (MOG) modified glassy carbon electrode (GCE) was reported to achieve super-sensitive malathion detection. Phytic acid-based Cu-Co bimetallic MOG (PA-Cu-Co composite) is a kind of three-dimensional porous material and has a large surface area and superior conductivity due to crosslinked network structure and bimetal composition. The obtained PA-Cu-Co/GCE sensor can easily bond malathion due to the good affinity between Cu element and sulfur groups of malathion, leading to an inhibited redox signal of Cu element in presence of malathion. The electrode reaction was a typical adsorption controlled process. The introduction of Co element not only greatly improves the electron transfer ability but increases surface area and active sites of sensor interface for high affinity of malathion, thus endowing PA-Cu-Co composite with outstanding sensitivity and selectivity. Under optimized operating conditions, the enzyme-free PA-Cu-Co/GCE malathion sensor exhibits good stability and excellent detection performance, with a wide linear range to malathion of 0.5 pM to 5 μM and low detection limit of 0.3 pM. Furthermore, the PA-Cu-Co/GCE sensor showed good recovery in real samples detection, implicating the potential applicability of PA-Cu-Co/GCE sensor in sensitive and selective detection of organophosphorus pesticides (OPs).